Vibratory drive systems

ABSTRACT

A mechanism for transforming a vibratory movement into a rotating movement, particularly for use in timepieces, wherein stepping pawls connected to a vibrating member act onto a ratchet wheel loosely mounted on the vibrating member for relative oscillation in the plane of vibration, the ratchet wheel being advanced by relative displacement between said vibrating member and stepping pawls respectively and said ratchet wheel due to the inertia of the latter. The rotating movement of the oscillating ratchet wheel is transmitted to a gear train by a magnetic coupling or transmission.

O United States Patent 1 3,691,754 Hetzel [451 Sept. 19, 1972 [54] VIBRATORY DRIVE SYSTEMS 3,540,205 11/1970 l-letzel ..58/23 [72] Inventor: Max Hem], Bienne Switzerland 3,540,206 11/1970 l-letzel ..76/126 [731 Assignw Lquis Brandt Primary Examiner-Richard B. Wilkinson Heme S-wtzerland Assistant Examiner-Edith C. Simmons Jackmon 22 Filed: Nov. 12, 1970 Attorney-mine & Smiley [30] Foreign Application Priority Data mechanism for transforming a vibratory movement into a rotating movement, particularly for use m Nov. 13, 1969 Switzerland ..'16873/69 timepieces, wherein stepping pawls connected to a vibrating member act onto a ratchet wheel loosely 53/23 58/23 mounted on the vibrating member for relative oscilla- 74/88 310/37, 331/156 tion in the plane of vibration, the ratchet wheel being [5 'f Cl "604C 3/02 F16}! 27/02 33/00 advanced by relative displacement between said [58] new of Search 8/23 23 23 23 1 l6; vibrating member and stepping pawls respectively and 74/15 310/37; 331/156 said ratchet wheel due to the inertia of the latter, The References Cited rotating movement of the oscillating ratchet wheel IS transmitted to a gear train by a magnetic coupling or transmission.

15 Claims, 9 Drawing Figures PATENTED I97? 3.691.754

sum 1 or 4 MAX HETZEL PATENTEDSEP 1 9 I972 SHEU 2 OF 4 x INVENTOR P'ATE'N'TEDsEP 1 9 I972 3.691.754

INVENTOR MAX HETZEL PATENTEDSEPIQIHTZ 3.691.754

SHEET k 0F 4 g 8 Fig. 7

H INVENTOR VIBRATORY DRIVE SYSTEMS vibrations of which are maintained by an electric drive.

In vibratory drive systems of this type, generally a vibratory member is fixed to an elastic arm permitting periodically occuring, substantially rectilinear movements of the vibratory member. According to the dimension and working condition, vibratory arm and vibratory member may be considered as a resonator. As it is well known, a resonator being in the vibratory condition of a certain resonance frequency is characterized by relatively high intrinsic energy and small transmission of energy outwards.

The invention includes also vibratory drive systems, the vibratory members of which are not operated in the condition of a resonance frequency.

In the most of the vibratory drive systems of the aforesaid type there is a driving pawl fixed to the vibratory member and oriented in the direction of vibration. This driving pawl engages the teeth of a ratchet wheel, the pivot bearing of which is arranged immovable relative .to the vibratory member. Moreover, a stepping pawl, the mounted end of which is also immovable relative to the vibratory member engages the teeth of the ratchet wheel.

The normal frequency of vibratory drive systems of the aforesaid type usually lies in the range of about 200 to 700 vibrations per second. The diameters of ratchet wheels of known construction are about 1 to 3 mm. Already these dimensions show that the parts of vibratory drive systems converting the periodic rectilinear movements into unidirectional rotary movements offer important technological problems to the designer. Such, e.g. the efficiency of the conversion of movements must be very high, namely for two reasons. The first reason consists in that the energy consumption of a vibratory drive system, e.g. for small watches is not allowed to exceed a predetermined value depending on the energy content of a battery of a decided size and commercial availability. The second reason lies in the fact that energy loss leads to the destruction of a vibratory drive system if the power dissipation exceeds a predetermined value. In order to attain high efficiency one must adjust most precisely the pawls relative to the ratchet wheel and select especially resistive materials. Unfortunately in known vibratory drive systems the adjustment of the pawls and the support of the ratchet wheel are subjected to undesired changes since generally the fixing points of vibratory member, ratchet wheel and stepping pawl are placed relatively far from each other on a base plate and all parts are subjected as well to thermic as to mechanic influences.

When vibratory drive systems of the aforesaid type serve as synchronous motors or even as time keeping elements for clocks a predetermined frequency of periodic movements or periodic current pulses of electric energy is converted into rotation of a predetermined number of revolutions. This expectation requires that the amplitudes of the movements of the vibratory member must be kept constant within certain limits and that the positions of the pawls and the ratchet wheel remain unchanged relative to each other within small limits. In the known vibratory drive systems it is very difficult to comply with the aforesaid requirements.

A further problem in vibratory drive systems of the aforesaid type is explicable by the fact that e.g. in the use for wrist watches the total transmission of energy should lie within the range of only a few microwatts. The useful forces thereby appearing in a vibratory drive system are accordingly small. Therefore, very small disturbing forces may lead to operating troubles. Such disturbing forces appear e.g. between the pawls and the ratchet wheel if between these parts there arise layers of liquids, such as water or oil, the molecular attraction of which in the form of surface tension and adhesion force may exceed the useful forces. The aforesaid layers of liquids arise by diffusion, i.e. volatilization of oil from oil-lubricated bearings of a watch and condensation on the ratchet wheel or by condensation of water vapor from moist air. If e.g. the bearings of a ratchet wheel are oil-lubricated the distance of diffusion is relatively short. In many cases the condensation of water vapor cannot be avoided even in waterproof clockcases.

It is an object of the invention to solve the. aforesaid problems andto provide a vibratory drive system, the production tolerances and working reliability of which are great, and the most sensible parts of which may be replaced upon operating troubles by use of simple means and by one possessing only limited knowledge and dexterity.

According to the invention the solution of the problem consists in that on a vibratory member two pawls are disposed nearly in parallel with the direction of vibration, said pawls engaging the teeth of a ratchet wheel. The ratchet wheel is movably disposed on said vibratory member and magnetically coupled to a coupling wheel supported by a stationary part. Under the influence of the mass inertia on the one hand and the accelerations by the vibratory member on the other hand at least in the direction of vibration ratchet wheel and pawls may be caused to perform reciprocal movements leading to unidirectional rotary movements of the ratchet wheel.

An especially advantageous embodiment of the vibratory drive system according to the invention is characterized in that the ratchet wheel concerning its rotation axis is movable relative to the vibratory member, while the pawls are fixed to the vibratory member. For the desired function, however, only relative movements are necessary between the pawls on the one hand and the ratchet wheel on the otherhand. Therefore, according to the invention also the ratchet wheel concerning its rotation axis could be fixed to the vibratory member, while only the pawls would be movable relative to the vibratory member. However, the known pawls have too small masses, while from the masses of the known ratchet wheels it may be expected right off that great enough useful forces will appear.

Preferably the pawls and the ratchet wheel are located within a closed sleeve detachably mounted on the vibratory member. The sleeve may be filled with a liquid having a low vapor pressure or low viscosity or with one of the known lubricating gases. Among suitable liquids for this purpose are silicone oils or solutions,

the constituents of which change the physical properties of the liquid, such as the surface tension and the wetability. The proposal of filling the sleeve with liquids seems to be very disadvantageous indeed with regard to previous statements. But really it is very advantageous that surface tensions can no longer appear as disturbing forces if the sleeve is totally filled with a liquid. Since liquids in themselves have a greater density than gases it is sure that in any case their composition is not changed even after a long period of time.

For magnetically coupling between ratchet wheel and coupling wheel in itself a pair of magnetic poles is necessary only on one wheel, while on the other wheel a ferromagnetic yoke could consist of magnetically soft material. Preferably the ratchet wheel comprises at least one pair of magnetic poles having a relatively high magnetic intensity. This pair of magnetic poles may be set right axially or radially according to the arrangement of the coupling wheel and the ratchet wheel relative to each other. An especially powerful coupling exists if the rotation axes of the ratchet wheel and the coupling wheel are arranged nearly in parallel with each other and if their reciprocal distance lies within the limits of the diameter of the smaller wheel. Then namely both wheels have the same direction of rotation, and corresponding poles remain always in the non-positive connection given once for all. The axis of the coupling wheel, however, may be displaced relative to that of the ratchet wheel in such a manner that both wheels rotate oppositely and roll off each on the other relative to virtual rotation radius. In the event of a coupling having a coupling wheel arranged coaxially to the ratchet wheel there appear no radial components of the magnetic forces disturbing the dynamics of the ratchet wheel.

If according to the invention the ratchet wheel is disposed on the vibratory member, and the vibratory member moves relative to the rotation axis of the coupling wheel the ratchet wheel moves relative to the coupling wheel. Thus, during operation the reciprocal distance of the rotation axes of both the wheels is changed periodically. The magnetic coupling may be dimensioned so that the transmission of the torque from the ratchet wheel to the coupling wheel is not affected by the periodical fluctuations of the distance between both the rotation axes, even if the amplitude of the rectilinear movements of the vibratory member relative to the dimension usual hitherto is substantially increased. In principle no special, additional conditions must be considered for the construction of the vibratory drive system according to the invention. If, however, the tolerances for the production and adjustment should be exceptionally great, the vibratory drive system includes stops expediently fixed to the vibratory member, said stops limiting the reciprocal mobility between ratchet wheel and pawls in the direction of vibration, and moreover the arrangement of the stops, the pawls and the ratchet wheel on the vibratory member being such that from one position of rest the reciprocal mobility in one direction is approximately one-fourth of the length of a tooth on the ratchet wheel and in the opposite direction approximately three fourth of the same length.

In absence of a claim to completeness the following advantages may be enlisted which are attainable by the invention, especially in the event that in an electric clock the vibratory drive system is used as time keeping element, the resonance vibrations of which are maintained by electric drive:

I. The pawls and the ratchet wheel are arranged together on a very small base plate so that the reciprocal positions of the parts are not substantially affectable either by thermic or mechanical disturbances.

2. Whereas hitherto in known vibratory drive systems the positions of the pawls relative to the ratchet wheel could be set right only during the operating condition, i.e. dynamically, in the vibratory drive system according to the invention the position of the pawls relative to the ratchet wheel is set right in the static state. This simplifies the production very substantially.

3. All sensitive component parts of the new vibratory drive system may be combined in a single component part insensitive per se, the production of which is therefore independent on the production of the other parts.

4. All component parts which may lead to operating troubles are included in the aforesaid insensitive component part which in the event of an operating trouble may be replaced without particular preliminary knowledge, tools and experiences.

5. The sensitive component parts may be withdrawn from atmospheric influences by enclosure thereof.

6. The component parts and bearings subjected to the greatest friction within an electric clock may be completely immersed in a bath of a lubricant therefore being subjected to minimal wear.

7. The tolerance limits for the hitherto most sensitive bearings of an electric clock have been considerably increased since e.g. bearing play may be systematically used to assure the proper function of the clock.

8. In the new vibratory drive system the frequency of the normal vibrations may be considerably increased, which is advantageous especially for the use as a time keeping element in an electric clock.

9. On the output of the new vibratory drive system the number of revolutions is independent of the amplitude of the rectilinear movements of the vibratory member and therefore also extensively independent of the stress by the gear train.

10. The. output of the new vibratory drive system the number of revolutions is less affectable by external shocks than is the case in the known vibratory drive systems, because in the new vibratory drive system in contrary to the known systems the number of revolutions is independent of the amplitude whereas in electric clocks utilizing known vibratory drive systems an amplitude disturbed by shocks returns only slowly to its normal value.

Further particulars of the invention are subsequently illustrated in detail by embodiments in connection with the appended drawings, in which:

FIG. 1' shows the parts of a vibratory drive system serving as a time keeping element of an electric timepiece, watch or timepiece, said parts being essential for the invention,

FIG. 2 is a detail of a vibratory drive system according to FIG. 1, illustrating the positions of the pawls and the ratchet wheel relative to the vibratory member,

FIGS. 3a to 3k show nine stages of periodically appearing operating conditions between pawls and ratchet wheel in a vibratory drive system according to the invention,

FIG. 4 is the top view of essential component parts of the vibratory drive motor according to FIG. 1, said component parts being installed in a sleeve cut open for the drawing,

FIG. 5 is a front view in section taken along the dotand-dash line V-V in FIG. 4,

FIG. 6 is a partial front view in section showing a modified embodiment of component parts of the vibratory drive system according to FIGS. 1, 4 and 5,

FIG. 7 is a partial front view in section showing an again modified embodiment of the vibratory drive system according to FIGS. 1, 4 and 5,

FIG. 8 is a schematical partial top view of another embodiment of the vibratory drive system according to the invention, and

FIG. 9 is a graph illustrating the reciprocal movements of mass points during the operation of the new resonance motor.

As shown in FIG. 1 apole shoe 1 encloses a coil 2 and forms togetherwith the latter the essential component parts of an electromechanical energy converter. The pole shoe 1 has on its insides magnets, the magnetic flux of which cuts the windings of the coil 2. The coil is mounted on a coil core 3, in'the interior of which inknown-manner the parts of an electric oscillator-circuit may be arranged, the output of which is connected to the ends of the coil. Screws 4 and 5 serve for the fastening of coil core and coil to a base plate not designated in particular. To the same base plate there is fixed the end (also not designated) of a vibratory arm 6, the free end of which carries a vibratory body 7 in turn bearing pole shoe 1. Strictly speaking, in practice the individual parts 1, 6 and 7 are connected to each other by soldering or bonding.

The pole shoe 1, the vibratory body 7 and the vibratory arm 6 together form the one half of a mechanical resonator in the aforesaid sense. In the vibratory arm 6 the accumulated intrinsic energy of the resonator appears in form of elastic forces. The second half of the resonator is not shown and may be advantageously disposed axial symmetrically to the first half. Thereby then a further pole shoe encloses the windings of the same coil 2. In the described form the resonator and in the coil core 3 the oscillator-circuit controlled by the resonator serve as drive system and simultaneously as the time keeping element of an electric wrist watch. 0n the vibratory body there is arranged a substantially circular cylindrical sleeve 8 wherein a ratchet wheel 9 and two pawls 10 and 11 are enclosed. With respect to the depiction of FIG. 1 the ratio of sizes, especially of the pawls and the ratchet wheel are very distorted and the latter are only schematically indicated. In every case it should be recognizable that the pawls are positioned approximately parallel to each other and to the main direction of vibration of the vibratory body 7. The rotation axis of the ratchet wheel 9 is approximately perpendicular thereto.

The sleeve 8 is preferably gastight closed. The ratchet wheel 9 transfers magnetically a torque to a coupling wheel 12, which is arranged out of the sleeve 8 and is also shown only schematically. The rotation axis of the coupling wheel 12 is designated by a cross 13 and extends approximately in parallel with that of the ratchet wheel 9, however far beyond the reach of the ratchet wheel, which envolves certain constructive advantages. As already stated in the general description, the coupling wheel could also be arranged approximately coaxial to the ratchet wheel 9. In this case, however, its magnetically effective diameter would be limited approximately to that of the ratchet wheel. The coupling wheel 12 may be connected to the gear train and the hands of a timepiece, watch or clock. Wheels 9 and 12 are permanently magnetized with poles as shown in FIG. 1

In FIG. 2 it should initially be observed that only the ratio of sizes of the two rows 16 and 17 and of the diameter of a bore-hole 18 of a ratchet wheel 19, further of the diameter of a pivot 20, two pawl stones 21 and 22, and two pawls 23 and 24 are approximately to scale. Otherwise the ratchet wheel 19 is shown considerably distorted. Two dash lines 25 and 26 connect the two tooth rows 16 and 17 and should be taken to indicate that the two rows merge into one another on the periphery of the ratchet wheel. The pivot 20 is fixed to a base plate in the same manner as the (not shown) ends of the .pawls 23 and 24. The difference between the diameters of the bore-hole 18 and the pivot 20 amounts approximately to the length of a tooth of a tooth row 16 and 17, which corresponds to a pitch.

In FIG. 2 there is shown the neutral positionof the individual component parts relative to each other. The component parts are in the neutral position if there is no relative movement between them and if no other acceleration than the acceleration due to gravity acts on them. According to the invention crossmarked axis of the bore-hole 18 should have a distance from an also cross-marked axis of the pivot 20 in the order of magnitude of a quarter of the length of a tooth of the tooth rows 16 and 17 and in the order of magnitude of a quarter of a pitch, respectively. If the last named requirements are complied with, as well in the reach of the diameters of the bore-hole 18 and the pivot 20 as in the reach of the adjustment of the pawls 23 and 24 the production tolerance amounts i one quarter of the length of a tooth and a quarter of a pitch, respectively.

In the case in point the pawls 23 and 24 are fixed to the base plate on a point displaced from a position centrally symmetric to the pivot 20 in the direction of vibration by a quarter of the length of a tooth of the ratchet wheel 19.

In FIG. 3 the component parts according to FIG. 2 are shown only schematically and simplified. In order to render the representation less complex respective reference characters have been inserted only in FIG. 3f. Accordingly, the arrows in FIG. 3 represent the pawls 23 and 24. The representations in the form of steps are the tooth rows 16 and 17. The more or less eccentric rings represent the peripheral lines of the borehole 18 and the pivot projecting into the bore-hole.

FIG. 3a shows the neutral position corresponding to FIG. 2. In the neutral position the free ends of the two pawls touch two diametrically disposed tooth profiles of the two tooth rows.

FIG. 3b shows a position which occurs if the vibratory member, the pawls and the pivot have moved to the right and if the pivot 20 and the pawl 23 put a force on the ratchet wheel 19 accelerating the latter. In this position the pivot 20 has covered a distance of a quarter of one pitch compared with the position according to FIG. 3a and relative to the ratchet wheel 19, while the pawl 24 has covered the double distance, i.e.

approximately the distance of a half of one pitch with regard to the tooth profile which it had touched previously.

FIG. 3c shows the dynamic position of the component parts at a later point of time, wherein the ratchet wheel 19 continues moving to right, while the acceleration of the pawls and the pivot controlled by the vibratory member is already reversed. As soon as the pivot is again concentric to the bore-hole 18 of the ratchet wheel 19 the pawl 24 strikes at the aforesaid tooth profile of the tooth row 17, while the pawl 23 has retired from the tooth profile touched previously by the length of the half of one ptch.

Upon further movement of pivot and pawls relative to the ratchet wheel to left the component parts reach a position according to FIG. 3d, wherein the pawl 24 touches the same tooth profile furthermore and put a left-directed force on the ratchet wheel, while the pawl 23 is on the end of the tooth, upon which it lay hitherto. In this position the pawl 23 falls from one tooth to the next one. During the period of time between the positions according to FIGS. 3c and 3d the pivot has covered a distance only of a quarter of a pitch relative to the ratchet wheel, while the pawl 23 has been able to cover the double distance, i.e. the half of one pitch relative to the ratchet wheel. In this connection it should be pointed out that due to the given construction the covered absolute distance of both the pawls and the pivot is identical and controlled by the vibratory member. The different illustrations in FIG. 3, however, concern the distances relative to the ratchet wheel, which rests now on the free end of the one pawl and now on the free end of the other pawl and rotates about these free ends in mutual directions.

The dynamic operating condition shown in FIG. 3e corresponds to that shown in FIG. 3b, however with the difference that directions of forces and movements of the second conditions are opposite to those of the first condition. A further and remarkable difference consists also in the fact that in the position according to FIG. 3e compared with the position according to FIG. 3b the ratchet wheel is advanced by one tooth relative to the pawl 23.

In the position according to FIG. 3f the center of gravity of the ratchet wheel 19 still continues to move to the left, while pivot and pawls compared with the position according to FIG. 3e are already subjected to an opposite'acceleration.

The position according to FIG. 33 corresponds to that according to FIG. 3c, however with reversed situations relating to the accuring forces and accelerations. To make clearer the function one must always consider that in the position according to FIG. 3d the occurrence of the proceeding ratchet wheel relative to the pawl 23 is irreversible and that the stated equivalents between different dynamic positions during the proceeding time cannot confirm the reversibility of all intermediate occurrences. A certain periodicity occurs only at times after one revolution of the ratchet wheel.

The dynamic position according to FIG. 3h corresponds to that according to FIG. 3d, however with opposite direction of the forces and accelerations. In the position according to FIG. 3h the pawls 23 and 24 have also interchanged their functions compared with the position according to FIG. 3d. In the recent case namely the pawl 24 is falling from -one tooth of ,the tooth row 17 to the next tooth, which fact is physically more exactly called a proceeding of the ratchet wheel by one tooth relative to the pawl 24. The rotation of the ratchet wheel relative to the pawls 23 and 24, and the base plate and the vibratory member, respectively, amounts totally one pitch between the operating conditions according to FIGS. 3a and 3h. Apart from the irreversible rotation of the ratchet wheel by this pitch the dynamic operating condidtion according to FIG. 3h is completely comparable with that according to FIG. 3a.

The FIGS. 3i and 3k show the same dynamic operating condition as the FIG. 3b. Both the last named figures are different from each other only by a displacement of the stairs representing the tooth rows 16 and 17 relative to the periphery of the bore-hole 18. This formally necessary displacement demonstrates obviously the proceeding of the ratchet wheel by one pitch relative to'the pawls and the pivot.

By means of FIG. 3 also the conditions described in connection with FIG. 2 may be clarified and the statement concerning the tolerances to be observed may be established.

According to the illustration shown in FIG. 4 two pawls 31 and 32 engage the teeth of a ratchet wheel 33. Each of two different adjusting members 34 and 35 keeps a pawl in its positionapproximately parallel with the other and parallel with the main direction of vibration of the vibratory member. Both the adjusting members represent two different possibilities of construction, each of which has its special advantages and disadvantages.

The adjusting member 34 is fixed to a bottom 36 of a sleeve 37 by means of three bolts 38, 39 and 40. Clearly member 34 may be fixed to bottom 36 by soldering or other fixing means. The free end of the adjusting member 34 lies upon an eccentric bolt 41 driven in a bore-hole 43 of the bottom 36. The adjusting member 34 functions by its elasticity. In any case the adjusting member borders on the eccentric bolts with acertain pre-Ioad. If e.g. the eccentric bolt 41 is wrenched by means of a screw driver the free end of the adjusting member is displaced and thereby also the free end of the pawl 31.

0n the other hand a pivot 44 is fixed to the adjusting member 35, said pivot being put in a respective borehole of the bottom 36. Thus, the free end of the adjusting member 35 and therewith the free end of the pawl 32 may be moved by turning on the adjusting member in the reach of its pivot 44. However, by the adjusting member 35 the position of the pawl 32 cannot be adjusted so exactly as the position of the pawl 31 by the adjusting member 34. But this disadvantage is compensated by the exceptional simplicity of the construction of the adjusting member 35.

For purposes of clarity the eccentric bolt 43, the two adjusting members 34 and 35 and the two pawls 31 and 32 have been omitted in FIG. 5. In FIG. 5 there are recognizable the specific features of the construction of a hub 46, on which the ratchet wheel 33 is fitted. The hub consists of ferromagnetic material having a high coercitivity and comprises at least one pair of magnetic poles. Thus, the hub may also be named a pole wheel. Hitherto pole wheels having one or two pairs of poles on their perphery have turned out. Thereby on the periphery poles of mutually polarity succeed.

A pin 48 projects into a bore-hole 47 of the hub 46, said pin being fastened in a respective bore-hole of the base plate 36. The difference between the diameters of the bore-hole 47 and the pin 48 amounts approximately the half of a pitch of the ratchet wheel 33.

The hub 46 touches the surface of a flat watch stone 49 only with one edge on its periphery, said watch stone being also fixed to the base plate 36 of the sleeve 37. A further edge 50 of the hub 46 faces a cover plate 51, which is inserted in a flanging edge 52 of the sleeve 37 and covers the sleeve. The cover plate may consist of a mineral material, preferably of the material of the watch stones. Obviously the material of the cover plate 51 similarly to that of the sleeve must not be ferromagnetic so that the magnetic coupling between the hub 46 and a coupling wheel positioned outside of the sleeve 37 is not disturbed. The sleeve 37 together with its content may be identical with the sleeve 8 and its content according to FIG. 1. In this case the coupling wheel can be in non-positive connection with the hub 46 and the ratchet wheel 33.

In the embodiment according to FIG. 6 a ratchet wheel 55 and a magnet wheel 56 having a joint center of gravity are fixed to a wheel axle 57. The one end of -this wheel axle is supported in a stone-bearing 58 without substantial play. A stone-bearing 59 surrounds the other end of the wheel axle, namely with a play in the magnitude of one pitch of the ratchet wheel 55. On the other hand the two stone-bearings 58 and 59 are positioned in a bottom plate 60 and cover plate 61 of a sleeve.

During the operation the ratchet wheel 55 and the magnet wheel perform nutations together with the wheel axle 57.

In the embodiment according to FIG. 7 a ratchet wheel 62 and a magnet wheel 63 are fixed to a wheel axle 64, the one end of which projects into a stonebearing 65 and the other end of which is surrounded by a stone-bearing 66. The two stone-bearings are positioned in a bottom plate 67 and a cover plate 68 of a sleeve.

Between the wheel axle 64 and the two bearings 65 and 66 there is a play of the magnitude of one pitch of the ratchet wheel 62. During the operation accordingly the ratchet wheel 62, the magnet wheel 63 and the wheel axle 64 move periodically parallel to the axis.

In the embodiment according to FIG. 8 in the axial direction of a ratchet wheel 70 there are no stops stationary relative to the ratchet wheel. During the operation of this ratched wheel movements transverse to the axis are rather limited by cage walls 71 and 72 and pawls 73 and 74. This kind of construction is advantageous especially if the individual component parts of the vibratory drive system are very small and the tolerances lie in the microscopic range.

In the graph according to FIG. 9 the amplitude of a virtual center of the vibratory member and of a center of gravity of ratchet wheel and magnet wheel of the vibratory drive system according to the invention are plotted against time. The curve 76 represented by solid line concerns the virtual center of the vibratory body, while the curve 77 represented by a dash line represents the movement of the center of gravity of ratchet wheel and magnet wheel. The relationship of the two curves to one another is noteworthy especially in connection with FIG. 2 of the drawings. The virtual center, the movement of which is represented by the curve 76 lies as shown in FIG. 2 on the middle axis 28, while the center of gravity of ratchet wheel and magnet wheel lies as shown in FIG. 2 on the rotation axis 27. Supposing to a first approximation that the two axes move only parallel to the axis, immediately one can relate the curve 76 to the middle axis 28 and the curve 77 to the rotation axis 27. Then, it only remains to insure that in a plane perpendicular to the axes the curves represent only a single component of movement, namely that in the main direction of vibratory movements of the vibratory member.

The curve 76 is a sine curve corresponding to the practice if the vibratory member is associated with a mechanical resonator. In the graph according to FIG. 9

the time axis represents the neutral position of the middle axis according to FIG. 2 and the neutral position of the vibratory member, respectively.

If during the dynamic condition the middle axis 28 runs through the neutral position, the individual component parts are in a position with respect to each other corresponding approximately to that according to FIG. 3b. Thereby the rotation axis 27 follows the middle axis 28 in a distance of about a half of a pitch. This working condition is represented in the graph according to FIG. 9 by the points 78 and 79. At the point 78 there occurs an inversion of the acceleration for the middle axis 28, while the rotation axis 27 maintains the reached speed at point 79. Therefore, the movement of the rotation axis from the point 79 may be represented by a straight line, namely to a point 80. At the point 80 the rotation axis 27 has been displaced in advance of the middle axis 28 by the length of one pitch. This working condition corresponds to the representation in FIG. 3e.

From the point 80 the movement of the middle axis 28 determines also the movement of the rotation axis 27. Therefore from the point 80 the curve 77 is continued by a sine curve, namely to a point 82 lying vertically above the point of intersection 83 of the curve 76 with the time axis.

At the point 83 there occurs an inversion of the acceleration for the middle axis 28, while at point 82 the rotation axis maintains the reached speed up to a point 84 of the curve 77 Accordingly in this reach the curve 77 changes into a straight line. The position of the component parts with respect to each other according to FIG. 3i corresponds to the working condition accord ing to point 84.

From point 84 the movement of the rotation axis 27 is again completely determined by the movement of the middle axis 28. Accordingly from point 84 the curve 77 changes into a sine curve, namely to a point 86 lying vertically below the point of intersection 87 of the curve 76 with the time axis.

Two points of intersection 88 and 89 of the two curves 76 and 77 represent the working conditions being the basis of the FIGS. 30 and 33.

For curve 77 the effect of friction and the pawls interaction with the ratchet wheel have been not considered. Therefore the association of certain points of the two curves with certain positions of the component parts according to FIG. 3 is not quite precise. When for the curve 77 friction is considered the points 80 and 84 are displaced to the right on the sinusoidal sections of the curve. Obviously thereby the sections of the curve lying between the points 79 and 80 on the one hand and between the points 82 and 84 an the other hand cannot be straight lines. When the influences of the pawls are considered besides the discontinuities at the points 80 and 84 further discontinuities occur.

Generally it can be stated that the movement of ratchet wheel and magnet wheel and the movement of the rotation axis 27, respectively, lies in a segment limited by two continuous sine curves. The one continuous sine curve comprises the section lying between the points 80 and 82 of the curve 77. The other continuous sine curve comprises the section lying between the points 84 and 86 of the curve 77. Thus, the range of movement of the rotation axis 27 lies in a band following the curve 76, the width of said band in the direction of the amplitude amounts approximately one pitch as shown in FIG. 9. 1

Although above the invention has been illustrated by way of examples for the time measurement, there are possible also advantageous applications besides the timemeasurement.

What we claim is:

l. A vibratory drive system for use in timepieces comprising in combination:

a vibratory member;

a pair of pawls mounted on said vibratory member and oriented with their longitudinal axes parallel to the direction of vibration of the member;

a ratchet wheel movably mounted on said vibratory member, said pawls on opposite sides engaging the teeth of said wheel; and

a coupling wheel for transmitting said drive to a gear train, said wheel being mounted for rotation on an axis which is stationery with respect to said vibratory member, said coupling wheel being magnetically coupled to said ratchet wheel for driving thereby;

whereby said ratchet wheel and pawls may be set in reciprocal motions at least in the direction of vibration under the influence of the mass-moment .of inertia on the one hand, and to acceleration by the vibratory member on the other hand, said reciprocal motions resulting in uni-directional movement of said ratchet wheel.

2. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel is movable relative to the vibratory member with respect to its axis of rotation, while the pawls are fixed with respect to the vibratory member.

3. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel comprises a hole, in which a pivot fixed to the vibratory member projects, the cross section of said pivot being smaller than that of the hole.

4. A vibratory drive system as set forth in claim 3, wherein the hole is formed as a concentric bore-hole of the ratchet wheel and the pivot is formed as a circular cylinder.

5. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel is fixed'to a wheel axle, at least one end of which projecting into an axle bearing, the free diameter of said axle bearing being greater than that of the wheel axle.

6. A vibratory drive system as set forth in claim I, wherein the ratchet wheel is arranged in a cage, the clearance of which in the direction of the vibration is greater than the diameter of the ratchet wheel.

7. A vibratory drive system as set forth in claim I,

wherein stops limiting the reciprocal mobility between ratchet wheel and pawls in the direction of vibration are fixed to the vibratory member, and wherein the stops, the pawls and the ratchet wheel are disposed on the vibratory member in such a manner that from a neutral position the reciprocal mobility in one direction amounts approximately a quarter of the length of a tooth of the ratchet wheel and in the opposite direction approximately three quarters of the same length.

- 8. A vibratory drive system as set forth in claim 4, wherein the play between bore-hole and pivot, i.e. the difference of the diameters of bore-hole and pivot amounts approximately the length of a tooth of the ratchet wheel, and wherein the pawls are fixed to the vibratory member at a point displaced in the direction V the vibratory member at a point displaced in the direction of vibration by a quarter of the length of a tooth of the ratchet wheel from a position centrally symmetric to the pivot.

10. A vibratory drive system as set forth in claim 1, wherein pawls and ratchet wheel are arranged in a closed sleeve detachably mounted on the vibratory member.

11. A vibratory drive system as set forth in claim 1, wherein at least one pair of magnetic poles is located on the vibratory member.

12. A vibratory drive system as set forth in claim 10, wherein the sleeve is filled with a liquid having a low vapor pressure and a low viscosity.

13. A vibratory drive system as set forth in claim 12, wherein the sleeve is filled with silicon oil.

14. A vibratory drive system as set forth in claim 12, wherein the sleeve is filled with a solution.

15. A vibratory drive system as set forth in claim 1, wherein the vibratory member is a part of a mechanical resonator forming the time keeping element of an electric timepiece the resonance vibrations of said mechanical resonator being maintained by electric drive. 

1. A vibratory drive system for use in timepieces comprising in combination: a vibratory member; a pair of pawls mounted on said vibratory member and oriented with their longitudinal axes parallel to the direction of vibration of the member; a ratchet wheel movably mounted on said vibratory member, said pawls on opposite sides engaging the teeth of said wheel; and a coupling wheel for transmitting said drive to a gear train, said wheel being mounted for rotation on an axis which is stationery with respect to said vibratory member, said coupling wheel being magnetically coupled to said ratchet wheel for driving thereby; whereby said ratchet wheel and pawls may be set in reciprocal motions at least in the direction of vibration under the influence of the mass-moment of inertia on the one hand, and to acceleration by the vibratory member on the other hand, said reciprocal motions resulting in uni-directional movement of said ratchet wheel.
 2. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel is movable relative to the vibratory member with respect to its axis of rotation, while the pawls are fixed with respect to the vibratory member.
 3. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel comprises a hole, in which a pivot fixed to the vibratory member projects, the cross section of said pivot being smaller than that of the hole.
 4. A vibratory drive system as set forth in claim 3, wherein the hole is formed as a concentric bore-hole of the ratchet wheel and the pivot is formed as a circular cylinder.
 5. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel is fixed to a wheel axle, at least one end of which projecting into an axle bearing, the free diameter of said axle bearing being greater than that of the wheel axle.
 6. A vibratory drive system as set forth in claim 1, wherein the ratchet wheel is arranged in a cage, the clearance of which in the direction of the vibration is greater than the diameter of the ratchet wheel.
 7. A vibratory drive system as set forth in claim 1, wherein stops limiting the reciprocal mobility between ratchet wheel and pawls in the direction of vibration are fixed to the vibratory member, and wherein the stops, the pawls and the ratchet wheel are disposed on the vibratory member in such a manner that from a neutral position the reciprocal mobility in one direction amounts approximately a quarter of the length of a tooth of the ratchet wheel and in the opposite direction approximately three quarters of the same length.
 8. A vibratory drive system as set forth in claim 4, wherein the play between bore-hole and pivot, i.e. the difference of the diameters of bore-hole and pivot amounts approximately the length of a tooth of the ratchet wheel, and wherein the pawls are fixed to the vibratory member at a point displaced in the direction of vibration by a quarter of the length of a tooth of the ratched wheel from a position centrally symmetric to the pivot.
 9. A vibratory drive system as set forth in claim 5, wherein the difference between the diameters of wheel axle and axle bearing amounts approximately the length of one tooth, and wherein the pawls are fixed to the vibratory member at a point displaced in the direction of vibration by a quarter of the length of a tooth of the ratchet wheel from a position centrally symmetric to the pivot.
 10. A vibratory drive system as set forth in claim 1, wherein pawls and ratchet wheel are arranged in a closed sleeve detachably mounted on the vibratory member.
 11. A vibratory drive system as set forth in claim 1, wherein at least one pair of magnetic poles is located on the vibratory member.
 12. A vibratory drive system as set forth in claim 10, wherein the sleeve is filled with a liquid having a low vapor pressure and a low viscosity.
 13. A vibratory drive system as set forth in claim 12, wherein the sleeve is filled with silicon oil.
 14. A vibratory drive system as set forth in claim 12, wherein the sleeve is filled with a solution.
 15. A vibratory drive system as set forth in claim 1, wherein the vibratory member is a part of a mechanical resonator forming the time keeping element of an electric timepiece the resonance vibrations of said mechanical resonator being maintained by electric drive. 